Electronic pacemakers are used to artificially stimulate tissue such as the heart muscle with a pulsed electrical signal in order to correct or modify the heart's rhythm. Body implantable pacemakers are quite common, and generally comprise a small, self-contained housing or can which encloses a source of electrical energy (battery) and an electrical apparatus for producing electrical impulses at appropriate intervals. The pacemaker is implanted by making a subcutaneous cavity in which the housing is positioned. The housing is made with a thin width so that it makes as small a bulge as possible on the overlying skin. An electrode at one end of a catheter is implanted in the heart muscle. The other end of the catheter has a lead formed thereon which is electrically coupled to the pacemaker pulse generator to complete the pacemaker circuit.
Implantable electronic cardioverter/defibrillators are also available. Because of the increased energy requirements of these devices, they are usually significantly larger than implantable pacemakers. Consequently, it is advantageous for the connection between the implantable device and the catheter or lead to be as physically small as possible, permitting a more narrow profile for the device.
It is also important that the lead be connected to the pacemaker or defibrillator securely to prevent it from inadvertently decoupling. Both pacemakers and defibrillators may be removed and replaced as complete units without disturbing the implanted lead and electrode, so the lead connection must also be easily disconnected.
It has been common in the art to accomplish this by inserting an exposed terminal pin of the lead into an electrical terminal located at an inner end of a cylindrical bore in the pacemaker or defibrillator, which may be a header formed on the implantable device. The lead is then fixed in place by use of a set screw which extends through a tapped hole from the side of the header into the bore. Other alternatives have including resilient tabs, flanges or the like, such as may be shown in U.S. Pat. Nos. 4,259,962 and 4,112,953. A wedge-type connector is shown in U.S. Pat. No. 4,860,750. In addition, collet-type fasteners have been used heretofore. The collet-type fasteners previously used, however, had the significant disadvantage that they would lock on the lead, but could not be easily or reliably disengaged.